1. Field of the Disclosure
The present disclosure generally relates to pixel circuits and to a gain control circuit for linear-logarithmic (L-L) pixel sensors.
2. Brief Description of Related Art
Imaging systems often need to have pixels capable of handling a wide dynamic range to accommodate varying brightness levels of an imaged scene. Further, it may be desirable to control the signal conversion gain of pixel circuits to obtain large output signal voltage swings throughout the dynamic range of the pixel circuit. Several different pixel circuit architectures have been developed for this purpose. However, they generally increase pixel circuit complexity and present difficulties such as increased pixel size, non-linear response characteristics, and pixel-to-pixel signal deviations, among others. It is also desirable that the gain control of a pixel circuit be achieved without modifying any semiconductor process parameters such as dielectric layer thickness or substrate impurity profile.